In the field of slab continuous casting, casting of high-quality cast pieces of good surface and interior quality with high productivity requires prevention of operation trouble such as break-out. Break-out may be prevented as described below.
When a solidifying shell is completely sticked to the surface of a copper plate in a mold, the temperature of the solidifying shell decreases to the Curie point. Therefore, drawing of cast pieces may be temporarily stopped by detecting a decrease of the solidifying shell temperature to the Curie point to detect the sticking of the solidifying shell. Particularly, by applying a direct current magnetic field to the cast pieces in the mold to magnetize the solidifying shell and detecting a change in its line of magnetic force, it is possible to detect whether or not the temperature of the solidifying shell is decreased to the Curie point (for example see Patent Document 1).